drivers/staging/rtl8187se/ieee80211/ieee80211_crypt_ccmp.c

   1 /*
   2  * Host AP crypt: host-based CCMP encryption implementation for Host AP driver
   3  *
   4  * Copyright (c) 2003-2004, Jouni Malinen <jkmaline@cc.hut.fi>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation. See README and COPYING for
   9  * more details.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/random.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/if_ether.h>
  20 #include <linux/if_arp.h>
  21 #include <linux/string.h>
  22 #include <linux/wireless.h>
  23
  24 #include "ieee80211.h"
  25
  26 #include <linux/crypto.h>
  27 #include <linux/scatterlist.h>
  28
  29 MODULE_AUTHOR("Jouni Malinen");
  30 MODULE_DESCRIPTION("Host AP crypt: CCMP");
  31 MODULE_LICENSE("GPL");
  32
  33
  34 #define AES_BLOCK_LEN 16
  35 #define CCMP_HDR_LEN 8
  36 #define CCMP_MIC_LEN 8
  37 #define CCMP_TK_LEN 16
  38 #define CCMP_PN_LEN 6
  39
  40 struct ieee80211_ccmp_data {
  41         u8 key[CCMP_TK_LEN];
  42         int key_set;
  43
  44         u8 tx_pn[CCMP_PN_LEN];
  45         u8 rx_pn[CCMP_PN_LEN];
  46
  47         u32 dot11RSNAStatsCCMPFormatErrors;
  48         u32 dot11RSNAStatsCCMPReplays;
  49         u32 dot11RSNAStatsCCMPDecryptErrors;
  50
  51         int key_idx;
  52
  53         struct crypto_tfm *tfm;
  54
  55         /* scratch buffers for virt_to_page() (crypto API) */
  56         u8 tx_b0[AES_BLOCK_LEN], tx_b[AES_BLOCK_LEN],
  57                 tx_e[AES_BLOCK_LEN], tx_s0[AES_BLOCK_LEN];
  58         u8 rx_b0[AES_BLOCK_LEN], rx_b[AES_BLOCK_LEN], rx_a[AES_BLOCK_LEN];
  59 };
  60
  61 static void ieee80211_ccmp_aes_encrypt(struct crypto_tfm *tfm,
  62                                 const u8 pt[16], u8 ct[16])
  63 {
  64         crypto_cipher_encrypt_one((void *)tfm, ct, pt);
  65 }
  66
  67 static void *ieee80211_ccmp_init(int key_idx)
  68 {
  69         struct ieee80211_ccmp_data *priv;
  70
  71         priv = kzalloc(sizeof(*priv), GFP_ATOMIC);
  72         if (priv == NULL)
  73                 goto fail;
  74         priv->key_idx = key_idx;
  75
  76         priv->tfm = (void *)crypto_alloc_cipher("aes", 0, CRYPTO_ALG_ASYNC);
  77         if (IS_ERR(priv->tfm)) {
  78                 pr_debug("could not allocate crypto API aes\n");
  79                 priv->tfm = NULL;
  80                 goto fail;
  81         }
  82
  83         return priv;
  84
  85 fail:
  86         if (priv) {
  87                 if (priv->tfm)
  88                         crypto_free_cipher((void *)priv->tfm);
  89                 kfree(priv);
  90         }
  91
  92         return NULL;
  93 }
  94
  95
  96 static void ieee80211_ccmp_deinit(void *priv)
  97 {
  98         struct ieee80211_ccmp_data *_priv = priv;
  99
 100         if (_priv && _priv->tfm)
 101                 crypto_free_cipher((void *)_priv->tfm);
 102         kfree(priv);
 103 }
 104
 105
 106 static inline void xor_block(u8 *b, u8 *a, size_t len)
 107 {
 108         int i;
 109         for (i = 0; i < len; i++)
 110                 b[i] ^= a[i];
 111 }
 112
 113 static void ccmp_init_blocks(struct crypto_tfm *tfm,
 114                              struct ieee80211_hdr_4addr *hdr,
 115                              u8 *pn, size_t dlen, u8 *b0, u8 *auth,
 116                              u8 *s0)
 117 {
 118         u8 *pos, qc = 0;
 119         size_t aad_len;
 120         u16 fc;
 121         int a4_included, qc_included;
 122         u8 aad[2 * AES_BLOCK_LEN];
 123
 124         fc = le16_to_cpu(hdr->frame_ctl);
 125         a4_included = ((fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
 126                        (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS));
 127         /*
 128         qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
 129                        (WLAN_FC_GET_STYPE(fc) & 0x08));
 130         */
 131         qc_included = ((WLAN_FC_GET_TYPE(fc) == IEEE80211_FTYPE_DATA) &&
 132                        (WLAN_FC_GET_STYPE(fc) & 0x80));
 133         aad_len = 22;
 134         if (a4_included)
 135                 aad_len += 6;
 136         if (qc_included) {
 137                 pos = (u8 *) &hdr->addr4;
 138                 if (a4_included)
 139                         pos += 6;
 140                 qc = *pos & 0x0f;
 141                 aad_len += 2;
 142         }
 143         /* CCM Initial Block:
 144          * Flag (Include authentication header, M=3 (8-octet MIC),
 145          *       L=1 (2-octet Dlen))
 146          * Nonce: 0x00 | A2 | PN
 147          * Dlen */
 148         b0[0] = 0x59;
 149         b0[1] = qc;
 150         memcpy(b0 + 2, hdr->addr2, ETH_ALEN);
 151         memcpy(b0 + 8, pn, CCMP_PN_LEN);
 152         b0[14] = (dlen >> 8) & 0xff;
 153         b0[15] = dlen & 0xff;
 154
 155         /* AAD:
 156          * FC with bits 4..6 and 11..13 masked to zero; 14 is always one
 157          * A1 | A2 | A3
 158          * SC with bits 4..15 (seq#) masked to zero
 159          * A4 (if present)
 160          * QC (if present)
 161          */
 162         pos = (u8 *) hdr;
 163         aad[0] = 0; /* aad_len >> 8 */
 164         aad[1] = aad_len & 0xff;
 165         aad[2] = pos[0] & 0x8f;
 166         aad[3] = pos[1] & 0xc7;
 167         memcpy(aad + 4, hdr->addr1, 3 * ETH_ALEN);
 168         pos = (u8 *) &hdr->seq_ctl;
 169         aad[22] = pos[0] & 0x0f;
 170         aad[23] = 0; /* all bits masked */
 171         memset(aad + 24, 0, 8);
 172         if (a4_included)
 173                 memcpy(aad + 24, hdr->addr4, ETH_ALEN);
 174         if (qc_included) {
 175                 aad[a4_included ? 30 : 24] = qc;
 176                 /* rest of QC masked */
 177         }
 178
 179         /* Start with the first block and AAD */
 180         ieee80211_ccmp_aes_encrypt(tfm, b0, auth);
 181         xor_block(auth, aad, AES_BLOCK_LEN);
 182         ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
 183         xor_block(auth, &aad[AES_BLOCK_LEN], AES_BLOCK_LEN);
 184         ieee80211_ccmp_aes_encrypt(tfm, auth, auth);
 185         b0[0] &= 0x07;
 186         b0[14] = b0[15] = 0;
 187         ieee80211_ccmp_aes_encrypt(tfm, b0, s0);
 188 }
 189
 190 static int ieee80211_ccmp_encrypt(struct sk_buff *skb, int hdr_len, void *priv)
 191 {
 192         struct ieee80211_ccmp_data *key = priv;
 193         int data_len, i;
 194         u8 *pos;
 195         struct ieee80211_hdr_4addr *hdr;
 196         int blocks, last, len;
 197         u8 *mic;
 198         u8 *b0 = key->tx_b0;
 199         u8 *b = key->tx_b;
 200         u8 *e = key->tx_e;
 201         u8 *s0 = key->tx_s0;
 202
 203         if (skb_headroom(skb) < CCMP_HDR_LEN ||
 204             skb_tailroom(skb) < CCMP_MIC_LEN ||
 205             skb->len < hdr_len)
 206                 return -1;
 207
 208         data_len = skb->len - hdr_len;
 209         pos = skb_push(skb, CCMP_HDR_LEN);
 210         memmove(pos, pos + CCMP_HDR_LEN, hdr_len);
 211         pos += hdr_len;
 212
 213         i = CCMP_PN_LEN - 1;
 214         while (i >= 0) {
 215                 key->tx_pn[i]++;
 216                 if (key->tx_pn[i] != 0)
 217                         break;
 218                 i--;
 219         }
 220
 221         *pos++ = key->tx_pn[5];
 222         *pos++ = key->tx_pn[4];
 223         *pos++ = 0;
 224         *pos++ = (key->key_idx << 6) | (1 << 5) /* Ext IV included */;
 225         *pos++ = key->tx_pn[3];
 226         *pos++ = key->tx_pn[2];
 227         *pos++ = key->tx_pn[1];
 228         *pos++ = key->tx_pn[0];
 229
 230         hdr = (struct ieee80211_hdr_4addr *)skb->data;
 231         mic = skb_put(skb, CCMP_MIC_LEN);
 232
 233         ccmp_init_blocks(key->tfm, hdr, key->tx_pn, data_len, b0, b, s0);
 234
 235         blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
 236         last = data_len % AES_BLOCK_LEN;
 237
 238         for (i = 1; i <= blocks; i++) {
 239                 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 240                 /* Authentication */
 241                 xor_block(b, pos, len);
 242                 ieee80211_ccmp_aes_encrypt(key->tfm, b, b);
 243                 /* Encryption, with counter */
 244                 b0[14] = (i >> 8) & 0xff;
 245                 b0[15] = i & 0xff;
 246                 ieee80211_ccmp_aes_encrypt(key->tfm, b0, e);
 247                 xor_block(pos, e, len);
 248                 pos += len;
 249         }
 250
 251         for (i = 0; i < CCMP_MIC_LEN; i++)
 252                 mic[i] = b[i] ^ s0[i];
 253
 254         return 0;
 255 }
 256
 257
 258 static int ieee80211_ccmp_decrypt(struct sk_buff *skb, int hdr_len, void *priv)
 259 {
 260         struct ieee80211_ccmp_data *key = priv;
 261         u8 keyidx, *pos;
 262         struct ieee80211_hdr_4addr *hdr;
 263         u8 pn[6];
 264         size_t data_len = skb->len - hdr_len - CCMP_HDR_LEN - CCMP_MIC_LEN;
 265         u8 *mic = skb->data + skb->len - CCMP_MIC_LEN;
 266         u8 *b0 = key->rx_b0;
 267         u8 *b = key->rx_b;
 268         u8 *a = key->rx_a;
 269         int i, blocks, last, len;
 270
 271         if (skb->len < hdr_len + CCMP_HDR_LEN + CCMP_MIC_LEN) {
 272                 key->dot11RSNAStatsCCMPFormatErrors++;
 273                 return -1;
 274         }
 275
 276         hdr = (struct ieee80211_hdr_4addr *)skb->data;
 277         pos = skb->data + hdr_len;
 278         keyidx = pos[3];
 279         if (!(keyidx & (1 << 5))) {
 280                 if (net_ratelimit()) {
 281                         pr_debug("received packet without ExtIV flag from %pM\n",
 282                                  hdr->addr2);
 283                 }
 284                 key->dot11RSNAStatsCCMPFormatErrors++;
 285                 return -2;
 286         }
 287         keyidx >>= 6;
 288         if (key->key_idx != keyidx) {
 289                 pr_debug("RX tkey->key_idx=%d frame keyidx=%d priv=%p\n",
 290                          key->key_idx, keyidx, priv);
 291                 return -6;
 292         }
 293         if (!key->key_set) {
 294                 if (net_ratelimit()) {
 295                         pr_debug("received packet from %pM with keyid=%d that does not have a configured key\n",
 296                                  hdr->addr2, keyidx);
 297                 }
 298                 return -3;
 299         }
 300
 301         pn[0] = pos[7];
 302         pn[1] = pos[6];
 303         pn[2] = pos[5];
 304         pn[3] = pos[4];
 305         pn[4] = pos[1];
 306         pn[5] = pos[0];
 307         pos += 8;
 308
 309         if (memcmp(pn, key->rx_pn, CCMP_PN_LEN) <= 0) {
 310                 if (net_ratelimit()) {
 311                         pr_debug("replay detected: STA=%pM previous PN %pm received PN %pm\n",
 312                                  hdr->addr2, key->rx_pn, pn);
 313                 }
 314                 key->dot11RSNAStatsCCMPReplays++;
 315                 return -4;
 316         }
 317
 318         ccmp_init_blocks(key->tfm, hdr, pn, data_len, b0, a, b);
 319         xor_block(mic, b, CCMP_MIC_LEN);
 320
 321         blocks = (data_len + AES_BLOCK_LEN - 1) / AES_BLOCK_LEN;
 322         last = data_len % AES_BLOCK_LEN;
 323
 324         for (i = 1; i <= blocks; i++) {
 325                 len = (i == blocks && last) ? last : AES_BLOCK_LEN;
 326                 /* Decrypt, with counter */
 327                 b0[14] = (i >> 8) & 0xff;
 328                 b0[15] = i & 0xff;
 329                 ieee80211_ccmp_aes_encrypt(key->tfm, b0, b);
 330                 xor_block(pos, b, len);
 331                 /* Authentication */
 332                 xor_block(a, pos, len);
 333                 ieee80211_ccmp_aes_encrypt(key->tfm, a, a);
 334                 pos += len;
 335         }
 336
 337         if (memcmp(mic, a, CCMP_MIC_LEN) != 0) {
 338                 if (net_ratelimit())
 339                         pr_debug("decrypt failed: STA=%pM\n", hdr->addr2);
 340
 341                 key->dot11RSNAStatsCCMPDecryptErrors++;
 342                 return -5;
 343         }
 344
 345         memcpy(key->rx_pn, pn, CCMP_PN_LEN);
 346
 347         /* Remove hdr and MIC */
 348         memmove(skb->data + CCMP_HDR_LEN, skb->data, hdr_len);
 349         skb_pull(skb, CCMP_HDR_LEN);
 350         skb_trim(skb, skb->len - CCMP_MIC_LEN);
 351
 352         return keyidx;
 353 }
 354
 355
 356 static int ieee80211_ccmp_set_key(void *key, int len, u8 *seq, void *priv)
 357 {
 358         struct ieee80211_ccmp_data *data = priv;
 359         int keyidx;
 360         struct crypto_tfm *tfm = data->tfm;
 361
 362         keyidx = data->key_idx;
 363         memset(data, 0, sizeof(*data));
 364         data->key_idx = keyidx;
 365         data->tfm = tfm;
 366         if (len == CCMP_TK_LEN) {
 367                 memcpy(data->key, key, CCMP_TK_LEN);
 368                 data->key_set = 1;
 369                 if (seq) {
 370                         data->rx_pn[0] = seq[5];
 371                         data->rx_pn[1] = seq[4];
 372                         data->rx_pn[2] = seq[3];
 373                         data->rx_pn[3] = seq[2];
 374                         data->rx_pn[4] = seq[1];
 375                         data->rx_pn[5] = seq[0];
 376                 }
 377                 crypto_cipher_setkey((void *)data->tfm, data->key, CCMP_TK_LEN);
 378         } else if (len == 0)
 379                 data->key_set = 0;
 380         else
 381                 return -1;
 382
 383         return 0;
 384 }
 385
 386
 387 static int ieee80211_ccmp_get_key(void *key, int len, u8 *seq, void *priv)
 388 {
 389         struct ieee80211_ccmp_data *data = priv;
 390
 391         if (len < CCMP_TK_LEN)
 392                 return -1;
 393
 394         if (!data->key_set)
 395                 return 0;
 396         memcpy(key, data->key, CCMP_TK_LEN);
 397
 398         if (seq) {
 399                 seq[0] = data->tx_pn[5];
 400                 seq[1] = data->tx_pn[4];
 401                 seq[2] = data->tx_pn[3];
 402                 seq[3] = data->tx_pn[2];
 403                 seq[4] = data->tx_pn[1];
 404                 seq[5] = data->tx_pn[0];
 405         }
 406
 407         return CCMP_TK_LEN;
 408 }
 409
 410
 411 static char *ieee80211_ccmp_print_stats(char *p, void *priv)
 412 {
 413         struct ieee80211_ccmp_data *ccmp = priv;
 414         p += sprintf(p,
 415                      "key[%d] alg=CCMP key_set=%d tx_pn=%pm rx_pn=%pm format_errors=%d replays=%d decrypt_errors=%d\n",
 416                      ccmp->key_idx, ccmp->key_set,
 417                      ccmp->tx_pn, ccmp->rx_pn,
 418                      ccmp->dot11RSNAStatsCCMPFormatErrors,
 419                      ccmp->dot11RSNAStatsCCMPReplays,
 420                      ccmp->dot11RSNAStatsCCMPDecryptErrors);
 421
 422         return p;
 423 }
 424
 425 void ieee80211_ccmp_null(void)
 426 {
 427         return;
 428 }
 429 static struct ieee80211_crypto_ops ieee80211_crypt_ccmp = {
 430         .name                   = "CCMP",
 431         .init                   = ieee80211_ccmp_init,
 432         .deinit                 = ieee80211_ccmp_deinit,
 433         .encrypt_mpdu           = ieee80211_ccmp_encrypt,
 434         .decrypt_mpdu           = ieee80211_ccmp_decrypt,
 435         .encrypt_msdu           = NULL,
 436         .decrypt_msdu           = NULL,
 437         .set_key                = ieee80211_ccmp_set_key,
 438         .get_key                = ieee80211_ccmp_get_key,
 439         .print_stats            = ieee80211_ccmp_print_stats,
 440         .extra_prefix_len       = CCMP_HDR_LEN,
 441         .extra_postfix_len      = CCMP_MIC_LEN,
 442         .owner                  = THIS_MODULE,
 443 };
 444
 445
 446 int ieee80211_crypto_ccmp_init(void)
 447 {
 448         return ieee80211_register_crypto_ops(&ieee80211_crypt_ccmp);
 449 }
 450
 451
 452 void ieee80211_crypto_ccmp_exit(void)
 453 {
 454         ieee80211_unregister_crypto_ops(&ieee80211_crypt_ccmp);
 455 }